Gill tissues of all oyster were collected in MBL 1 buffer and proteinase K for DNA isolation by mollusc kit.

Placed all the tubes with gill tissues in 37 C for overnight.

Viscera with digestive glands and gonads, etc. were dissected and discarded to prevent decomposition of rest of body by enzymes. Rest of the body of each oyster was stored in 10X RNAlater solution by weight.